Determining Terbinafine in Plasma and Saline Using HPLC

A simple, sensitive, and accurate high-performance liquid chromatography (HPLC) method for the determination of terbinafine concentrations in small-volume plasma and saline has been developed. Following a liquid extraction using hexane, samples were separated by reversed-phase HPLC on a Symmetry Shield RP18 (5 µm) 4.6 mm × 100 mm column and quantified using ultraviolet detection at 224 nm. The mobile phase was a mixture of water, phosphoric acid, and triethylamine (pH 3.0), with acetonitrile (65:35, v/v), at a flow rate of 1.1 mL/min. The standard curve ranged from 5 to 1500 ng/mL for parrot plasma and 1 to 25 µg/mL for 0.9% saline. Intra- and inter-assay variability for terbinafine was less than 10% for both matrices, and the average recovery was greater than 90%. This method has been developed in parrot plasma and should be applicable to other species, making it useful to those investigators dealing with small sample volumes, particularly when conducting pharmacokinetic studies that require multiple sampling from the same animal. This method would also be valuable to aquariums that need to determine terbinafine concentrations in salt water.